1. Technical Field
The present invention relates to a carbon nanotube film and a production process thereof.
The invention also relates to a capacitor which is an electrical element utilizing such a carbon nanotube film.
2. Related Art
Carbon nanotubes have been expected to find wide application as next-generation materials that exhibit a variety of characteristics derived from its specific shape and structure.
Carbon nanotubes are in the form of a one-dimensional tube developed by winding a graphene sheet composed of 6-membered carbon ring. Carbon nanotubes having one graphene sheet are called single-walled carbon nanotube (SWCNT) and carbon nanotubes having multiple graphene sheets are called multi-walled carbon nanotube (MWCNT).
SWCNT is said to have a diameter of about 1 nm. MWCNT is normally said to have a diameter of about tens of nanometers. They are extremely finer than materials which have been heretofore called carbon fiber (diameter: from tens of nanometers to 1,000 nm).
Carbon nanotubes are also characterized in that they have a length on the order of micrometer (μm) and a very large aspect ratio of length to diameter.
Further, carbon nanotubes have 6-membered carbon rings aligned helically and thus are a material having so extremely rare characteristics that both metallic properties and semiconductivity are exhibited. In addition, carbon nanotubes have an extremely high electrical conductivity and thus allow the passage of current at a density of 100 MA/cm2 or more.
Carbon nanotubes are excellent in mechanical characteristics as well as electrical properties. In some detail, since carbon nanotubes are composed of only carbon atoms, they exhibit a Young modulus of more than 1 TPa and thus are extremely rigid despite its very low weight.
Thus, carbon nanotubes have various excellent properties and thus are a material which is extremely attractive as industrial material. Carbon nanotubes have found application in the art of electronic devices (electronic elements) such as flat panel display and transistor.
As actual methods for processing and film-forming carbon nanotubes according to device design there are known film-forming/patterning methods involving chemical vapor deposition method (CVD method), electrophoresis method, screen printing method with a mixture with a binder, or the like.